(Applicant's Abstract): The focus of this clinical project is to determine the pathophysiological basis for heightened surgical risk among post-radiation head and neck patients and the efficacy of hyperbaric oxygen (HB02) therapy for improving outcome. Two hypotheses are the basis for this proposal: (1) Predictive models can be developed for sub-groups of head and neck cancer patients who have undergone surgery based on tumor specific site, previous treatment, and co-morbidity to predict which patients will have complications defined as wound infection and fistula, and (2) HB02 given by a standard protocol can modify tissue hypoxia and vascularity that is present in patients with previous radiation therapy to the neck who have recurrent or secondary cancers requiring laryngectomy. Three specific aims will test these hypotheses: (1) Development of a detailed database model to predict the risk of developing post-operative complications in complex head and neck aerodigestive tract cancer resections, (2) Carry out prospective validation of the predictive model based on data collected from all patients treated at the University of Pennsylvania Head and Neck Cancer Center, (3) Determine whether hyperbaric oxygen therapy alters post-surgical complication rates and acute and long-term quality of life. These studies will include evaluation of clinical parameters, surgical outcome and quality of life measurements and objective, laboratory-based techniques to evaluate the magnitude of hypoxia/vascularization in surgical zones to provide objective data on surgical risk and clinical responses to a ourse of HB02 therapy.